Some plasma torch metal working operations require that the torch body remain close to hot metallic surfaces for prolonged periods of time. For example, in a gouging or cutting operation, the surface of the workpiece is raised to as high as 2000.degree. Fahrenheit. The nozzle positioned on the front end of the torch often is positioned only a fraction of an inch from the red-hot workpiece. As a result, the intense heat generated during cutting and gouging often degrades the torch body resulting in premature failure of the machined, high tolerance components of the torch.
Some torch designs have the torch body formed from a molded polymer material, such as phenolic resin, that encases the machined, high tolerance components of the torch. The phenolic resin provides some protection from the high heat and resists degradation and concomitant failure of the torch components. Over time, however, these heat-resistant resins degrade when the torches are used in cutting or gouging operations in which the nozzle is placed in close proximity to the hot metal workpiece.
Some prior art welding apparatus include flat, sheet metal shields secured onto electrode holders for protecting both the torch and the operator's hand from the heat generated during welding. These shields often are dimensioned large enough to provide some protection to the electrode holder and operator's hand. However, the shields do not provide protection if the electrode holder is positioned to within a fraction of an inch of a red hot workpiece. Thus, the shields are not advantageous for use with plasma torches. The prior art shields are not designed, nor configured to withstand the high heat imparted onto a torch body that is positioned to within fractions of an inch of a workpiece during metal cutting and gouging operations.
Additionally, the above prior art shields are large and unwieldy, and often make the particular metal working operation difficult because of the unwieldy nature of the shield. Also, the prior art shields often are secured to the electrode holder in a position that allows a user to view the work without having visual interference from the shield. As a result of this shield positioning, heat and splatter emitted from the hot workpiece during welding often engages the front portion of the holder resulting in its degradation if the holder is positioned close to the workpiece. Because the shields are substantially flat and do not extend in close proximity to the electrode holder, the shields do not provide for any insulating air gap between the shield and electrode holder.